Information recording/reproducing apparatus with security measure

ABSTRACT

When data are to be recorded on a recording medium having imparted thereto a medium ID that is identification information unique to the recording medium, an additional ID related to the medium ID is generated on the basis of the medium ID. Then, the data are encrypted and recorded on the medium along with the additional ID. In reproduction, the medium ID and the additional ID attached to the data are read out from the medium, and then compared to determine whether both of the medium ID and additional ID meet a predetermined matching condition. When the additional ID attached to the data has been determined as meeting the predetermined matching condition, the data is judged to be reproducible data. In this manner, it is possible to promptly determined whether or not the data recorded on the medium are fairly-recorded data, which can effectively prevent unfair use of the data.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to information recording apparatusfor recording data on a recording medium in encrypted form andinformation reproducing apparatus for reproducing data recorded on arecording medium, as well as programs to be executed by a computer forrecording and/or reproducing data to and from a recording medium.

[0002] In recent years, it has been widely popular to deliver variousdigital content, such as music and image content, via the Internet andvarious other communication networks. Under such an environment, anyinterested user can purchase or acquire desired content (e.g., musicpiece data) by downloading, via such a communication network, thedesired content from information provider that supply music content andthe like. Further, with recent advancement of data compressiontechniques, it is possible to record content, acquired via the Internet,on a physical medium (recording medium) with high quality. Under suchcircumstances and from the viewpoints of copyright protection etc.,there is a great demand today for techniques to effectively preventunfair or unauthorized copying and use of digital content.

[0003] As a technique for preventing such unfair or unauthorized copyingand use of digital content, it has been known to employ a recordingmedium having a unique medium ID imparted thereto, such as Smart Media(registered trademark). More specifically, it has been known that dataof downloaded content to be recorded on a recording medium are encryptedby use of the medium ID unique to the recording medium, and, inreproduction of the recorded content, the encrypted data of the contentare decrypted using the unique medium ID of the recording medium. Inthis case, if downloaded to the recording medium in a fair (rightful)manner, the content can be appropriately decrypted and reproduced fromthe recording medium, because the medium ID used for decrypting thecontent coincides with the unique medium ID used for encrypting thecontent. If, on the other hand, particular content is first downloadedto the recording medium in a fair (rightful) manner and then unfairly(unrightfully) copied from the recording medium to another recordingmedium, then the data of the content read out from the other recordingmedium can not be appropriately decrypted, because the medium ID uniqueto the other recording medium is different from the unique medium IDused for encrypting the content; thus, the content can not be reproducedfrom the other recording medium. In this way, the known technique canprevent unfair copying of the content.

[0004] However, the aforementioned conventionally-known technique isdisadvantageous in that, before all recorded data of content to bereproduced from a given recording medium have been decrypted, it can notdetermine whether the data are fairly-recorded data, i.e. reproducible(more specifically, reproduction-permissible) data. Because decryptingthe data is quite time-consuming, the conventionally-known techniquewould lack processing quickness.

SUMMARY OF THE INVENTION

[0005] In view of the foregoing, it is an object of the presentinvention to provide an information recording apparatus, informationreproducing apparatus and computer program which, through simple andefficient processing, can effectively prevent unfair or unauthorizedcopying, use, etc. of data.

[0006] In order to accomplish the above-mentioned object, the presentinvention provides an information recording apparatus, which comprises:an encryption section that encrypts data to be recorded on a recordingmedium; a generation section that, on the basis of a medium ID recordedon the recording medium as identification information unique to therecording medium, generates an additional ID related to the medium ID;and a recording section that records the encrypted data on the recordingmedium along with the additional ID.

[0007] The present invention also provides an information reproductionapparatus for reproducing data recorded on a recording medium, whichcomprises: a first readout section that reads out, from the recordingmedium, a medium ID recorded on the recording medium as identificationinformation unique to the recording medium, an additional ID related tothe medium ID being also recorded on the recording medium in attachedrelation to the data; a second readout section that reads out, from therecording medium, the additional ID attached to the data; adetermination section that compares the medium ID and the additional IDread out by the first and second readout sections and determines whetherboth the medium ID and the additional ID meet a predetermined matchingcondition. When the additional ID attached to the data has beendetermined by the determination section as meeting the predeterminedmatching condition, the data is judged to be reproducible.

[0008] With the arrangements that an additional ID, related to a mediumID recorded on a recording medium as identification information uniqueto the recording medium, is generated on the basis of the medium ID andencrypted data are recorded on the recording medium along with thethus-generated additional ID, the present invention can enhance thesecurity of the data recorded on the recording medium. Further, inreproduction, the present invention can promptly ascertain the fairnessor rightfulness of the data recorded on the recording medium by justcomparing the medium ID and additional ID to check the authenticity ofthe additional ID, without having to decrypt all of the data recorded onthe recording medium, thereby achieving high-speed processing.

[0009] The present invention may be constructed and implemented not onlyas the apparatus invention as discussed above but also as a methodinvention. Also, the present invention may be arranged and implementedas a software program for execution by a processor such as a computer orDSP, as well as a recording medium storing such a software program.Further, the processor used in the present invention may comprise adedicated processor with dedicated logic built in hardware, not tomention a computer or other general-purpose type processor capable ofrunning a desired software program.

[0010] The following will describe embodiments of the present invention,but it should be appreciated that the present invention is not limitedto the described embodiments and various modifications of the inventionare possible without departing from the basic principles. The scope ofthe present invention is therefore to be determined solely by theappended claims.

BRIEF DESCRIPTION OF THE DRAWWINGS

[0011] For better understanding of the object and other features of thepresent invention, its preferred embodiments will be describedhereinbelow in greater detail with reference to the accompanyingdrawings, in which:

[0012]FIG. 1 is a block diagram showing an example of network connectionin a music content supply system in accordance with an embodiment of thepresent invention;

[0013]FIG. 2 is a block diagram showing an example hardware setup of acomputer usable as a client terminal;

[0014]FIG. 3 is a functional block diagram showing functions explanatoryof exemplary data writing operations performed in the embodiment; and

[0015]FIG. 4 is a flow chart explanatory of exemplary data readingoperations performed in the embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] Whereas the present invention will be described hereinbelow asdirected to recording music piece data on a recording medium, the datato be recorded on the recording medium may be any other desired digitalcontent, such as image data. Further, although the present inventionwill be described in relation to recording and reproduction, to and froma recording medium, of music piece data downloaded from a music contentsupply system via a communication network, the invention is not solimited.

[0017]FIG. 1 is a block diagram showing an example of network connectionin a music content supply system in accordance with an embodiment of thepresent invention. FIG. 2 is a block diagram showing an example hardwaresetup of a computer (PC) usable as a client terminal.

[0018] In FIG. 1, a server 30 that supplies music piece data (musiccontent) is connected to a communication network X, and each of aplurality of client terminals 10 can access the server 30 via thecommunication network X. The server 30 is a music information providerhaving a plurality of music piece data sets or files (music content),which, in response to a music-piece-data supply request sent from anyone of the client terminals 10, transmits a user-desired music piecedata set to the client terminal 10. Each of the client terminals 10,connected to the server 30 via the communication network X, can acquirea user-desired music piece data set (music content) by downloading theuser-desired music piece data set from the server 30; the acquisitionmay be either on a chargeable basis or on a free-of-charge basis.External recording medium 20 is connected to each of the clientterminals 10, so that each of the client terminals 10 can record musicpiece data, downloaded from the server 30, on the external recordingmedium 20. In the present invention, each set or file of music piecedata to be recorded is imparted with an additional ID based on a mediumID unique to the recording medium 20 and then recorded on the recordingmedium 20 along with the additional ID, as will be later described indetail.

[0019] As shown in FIG. 2, each of the client terminal 10 includes a CPU1, to which are connected, via a communication bus 1B, a ROM 2, a RAM 3,a read/write circuit 4, a communication interface 5, a display controlcircuit 6, a tone generator circuit 7, a MIDI interface 8, an operatoroperation detection circuit 9, a hard disk drive (HDD) 1, etc. To theCPU 1 is also connected a timer 1A for signaling predetermined interrupttiming for timer interrupt processing and counting various times.External recording medium 20 is removably connected to the clientterminal 10 via the read/write circuit 4.

[0020] The CPU 1 executes various programs stored in any of memories,such as the ROM 2 and RAM 3. Among these programs are informationrecording and/or reproducing programs for use in the embodiment of thepresent invention, as will be later described.

[0021] Each of the client terminals 10 is connected via thecommunication interface (I/F) 5 to the communication network X, such asthe Internet, LAN or telephone line, and the client terminal 10 cancommunicate various content, such as various programs, music piece data,etc. with the server 30 via the communication network X. Any ofinformation recording and/or reproducing programs and various otherprograms for use in the embodiment of the present invention can also bedownloaded from the server 30 via the communication interface 5. In sucha case, the downloaded program etc. are stored in the hard disk device(HDD) 1 or the like, then transferred to the RAM 3 when the program isto be executed, and then actually executed under control of the CPU 1.Such arrangements facilitate addition, to the client terminal 10, of anyof the information recording and/or reproducing programs and variousother programs for use in the embodiment of the present invention,version upgrade of any of the programs, etc. Note that each music piecedata content downloaded from the server 30 is received via thecommunication interface 5, temporarily stored in the RAM 3, subjected tolater-described predetermined processing, such as encryption andimpartment of an additional ID, and then recorded on the externalrecording medium 20 via the read/write circuit 4. The music piece datacontent temporarily stored in the RAM 3 disappears after having beenrecorded on the recording medium 20.

[0022] The display control circuit 6 causes a display section 6A tovisually display various information under control of the CPU 1; forexample, the display section 6A is used to display a listing of one ormore music piece data sets (music piece data files) recorded on theexternal recording medium 20. The tone generator circuit 7 is capable ofgenerating tone signals on the basis of tone data given via thecommunication bus 1B, and each of the thus-generated tone signals isaudibly reproduced or sounded through a sound system 7A including anamplifier and speaker. Note that the tone generator circuit 7 maygenerate tone signals using any suitable conventionally-known tonesignal generation method, such as the waveform memory method, FM method,physical model method, harmonics synthesis method, formant synthesismethod, analog synthesizer method or analog synthesizer simulationmethod. Further, the tone generator circuit 7 may be implemented eitherby dedicated hardware or by software processing executed by the CPU 1.The MIDI interface (MIDI I/F) 8 is intended for input/output of datacomplying with the MIDI standard, via which the client terminal 10 isconnected with an external MIDI device 8A. Operator unit 9 includingvarious input operators, such as a keyboard and a mouse, are connectedto the operator operation detection circuit 9.

[0023] Note that the client terminal 10 may be in the form of a personalcomputer or any other suitable communication terminal. It is justnecessary that the client terminal 10 include means for performingbidirectional communication and means for writing and reading out datato and from the external recording medium 20 connected thereto.

[0024] As an example, the instant embodiment uses, as the externalrecording medium 20, Smart Media (registered trademark) or the likehaving previously recorded thereon a medium ID peculiar to, or uniqueto, the recording medium 20. In FIG. 2, exemplary recorded contents ofthe external recording medium 20 are illustrated in a conceptual manner.The medium ID 20 a unique to the external recording medium 20 isprestored in a predetermined storage region, such as the header, of themedium 20, and one or more music piece data files 20 b are storable in acontent storage region with an additional ID imparted to each of themusic piece data files 20 b.

[0025] The additional ID is a unique ID based on the above-mentionedmedium ID. By comparing the additional ID and medium ID, it is possibleto identify a recording medium on which the music piece data fileimparted with the additional ID should be recorded. The pre-recordedunique medium ID of the external recording medium 20 is read out via theread/write circuit 4, and an additional ID is generated on the basis ofthe thus read-out medium ID. In the instant embodiment, the medium ID ofeach external recording medium 20 is used also as the additional ID;that is, in each of the recording medium 20, the additional ID is set tocoincide with the medium ID. Namely, the medium ID read out via theread/write circuit 4 is imparted, as the additional ID, to each musicpiece data file to be recorded on the external recording medium 20.

[0026]FIG. 3 is a functional block diagram showing functions that areperformed by the above-mentioned information recording program executedby the CPU 1. The following paragraphs describe an operational sequenceof data recording processing performed on the external recording medium20, with reference to FIG. 3. Note that a reception section 40 shown inFIG. 3 corresponds to the communication interface 5 of FIG. 2, and areading section 43 and writing section 45 correspond to the read/writecircuit 4 of FIG. 2. Note that various kinds of encryption to bedescribed below may be performed by any suitable conventionally-knownmethods.

[0027] In response to a request given from any one of the clientterminals 10, the server 30 transmits, to the client terminal 10, amusic piece data file desired by the user of the client terminal 10,after encrypting the music piece data in accordance with a firstencryption method; the music piece data thus encrypted with the firstencryption method will be referred to as “first encrypted data”. Here,the music piece data are encrypted by the server 30 with such a firstencryption method, in order to achieve security of the data duringtransmission from the server 30 to the client terminal 10; the firstencryption method used by the server 30 may be any suitable encryptionmethod conventionally employed in data delivery via a communicationnetwork. The client terminal 10 receives the first encrypted data fromthe server 30 by means of the reception section 40, and decrypt thethus-received first encrypted data into the original music piece data bymeans of a first decryption section 41. The thus-decrypted music piecedata are data organized in a predetermined format, such as a standardMIDI file (SMF) composed of a series of event data.

[0028] The reading section 43 reads out the medium ID from the externalrecording medium 20 removably attached to the client terminal 10. Secondencryption section 42 encrypts the music piece data, given from thefirst decryption section 41, using the read-out medium ID and inaccordance with a predetermined second encryption method (i.e., methodusing the read-out medium ID, in a different manner from the firstencryption method, to encrypt the music piece data into form that cannot be decrypted unless the unique medium ID of the recording medium 20is used), to thereby generate second encrypted data. Thus encrypting themusic piece data by use of the unique medium ID of a given externalrecording medium 20 to which the music piece data are to be downloadedis preferable from the viewpoint of data security, because it canreliably prevent reproduction of the music piece data in the event thatthe data are copied unfairly or unrightfully to another recording mediumhaving a different medium ID.

[0029] Impartment section 44 creates or generates an additional IDcorresponding to, or related to, the medium ID read out by the readingsection 43; as noted earlier, in the instant embodiment, the medium IDof the recording medium is used also as the additional ID; that is, foreach of the recording medium 20, the impartment section 44 generates anadditional ID that coincides in content with the medium ID. Thethus-generated additional ID is imparted to the file of the secondencrypted data (i.e., music piece data encrypted in accordance with thesecond encryption method) given from the second decryption section 42.The writing section 45 writes, onto the external recording medium 20,the music piece data file of a single music piece, composed of theencrypted music piece data and additional ID given from the impartmentsection 44, as a single data set. If the music piece data file of eachmusic piece includes a header section storing the name of the musicpiece etc. and a data section storing the music piece data, theadditional ID may be stored in the header section. The music piece datafile of the music piece, thus written on the external recording medium20 as a single data set, is visually displayed, for example, as a singleicon on the display section 6A by means of the display control circuit6.

[0030] In the above-described manner, one or more music piece data filescan be recorded on each external recording medium 20, depending on therecording capacity of the recording medium 20. In the instantembodiment, each of the music piece data files stored on the sameexternal recording medium 20 has the same addition ID that coincideswith the unique medium ID of the recording medium 20.

[0031] Whereas, in the illustrated example of FIG. 3, the respectivefunctions of the above-mentioned sections 40-45 are performed throughsoftware processing by the CPU 1, they can of course be implemented bydedicated hardware devices.

[0032]FIG. 4 is a flow chart showing an exemplary operational sequencedefined by the above-mentioned information reproducing program executedby the CPU 1. This and following paragraphs describe an example ofprocessing for reproducing data recorded on an external recording medium20, with reference to the flow chart of FIG. 4. The CPU 1 of the clientterminal 10 reads out information of all music piece data files recordedon the external recording medium 20, creates a music piece selectionlisting (or music piece reproduction listing) on the basis of theread-out data, and visually displays the created music piece selectionlisting on the display section 6A of FIG. 2. Once the user of the clientterminal 10 selects a music piece to be reproduced from the displayedselection listing, the following operations are carried out.

[0033] The CPU 1 reads out the unique medium ID of the externalrecording medium 20 at step S1, and then reads out the additional IDimparted to the selected music piece data file at step S2. Although, inthe illustrated example, the unique medium ID of the external recordingmedium 20 is first read out followed by readout of the additional ID,the additional ID may be read out first. At next step S3, the read-outmedium ID and read-out additional ID are compared to each other todetermine whether or not both of the medium ID and additional ID meet apredetermined matching criterion or condition (in the instantembodiment, whether the medium ID and additional ID coincide with eachother). If answered in the affirmative at step S3, the CPU 1 goes tosteps S4 and S5, where the selected music piece data file is judged tobe a reproducible object.

[0034] At step S4, the selected music piece data file is decrypted intothe original music piece data in accordance with a second decryptionmethod corresponding to the second encryption method with which themusic piece data were encrypted; in the illustrated example, theselected music piece data file is decrypted in accordance with thesecond decryption method using the medium ID. Then, at step S5, the CPU1 initiates reproduction of the decrypted music piece data.

[0035] If, on the other hand, the read-out medium ID and additional IDdo not meet the predetermined matching criterion or condition asdetermined at step S3, the CPU 1 branches to step S6, where itindicates, by visual display on the display section 6A, voices orotherwise, that the selected music piece data file is not reproducible,after which the reproduction processing is brought to an end.

[0036] In the instant embodiment, because the medium ID and additionalID are set to coincide with each other, the decryption can be performedaccurately through the operations of steps S4 and S5 of FIG. 4 when themusic piece data, downloaded and recorded to the external recordingmedium 20 fairly or rightfully from the server 30, are to be reproducedfrom the recording medium 20. If, on the other hand, the externalrecording medium 20 to be used for reproduction has the music piece dataunfairly or unrightfully copied from another recording medium, to whichthe music piece data were downloaded in a fair or rightful manner, thenthe unique medium ID of the external recording medium 20 to be used forreproduction differs from the additional ID imparted to the music piecedata to be reproduced, so that the CPU 1 branches from step S3 to stepS6. At step S6, it is promptly indicated to the user that the musicpiece data file is not reproducible; thus, in this case, the decryptionoperation of step S4 is not carried out at all. Namely, the instantembodiment of the present invention can promptly and readily determinewhether or not the music piece data recorded on the recording medium 20is a reproducible object, without actually decrypting the music piecedata. As a result, the instant embodiment can perform the reproductionprocessing with an increased efficiency.

[0037] As a modification of the operational sequence of FIG. 4, a listediting process may be added, in a flow path following step S6, foreffecting marking, deletion or the like of the music piece to bereproduced in the above-mentioned music piece reproduction listing. Inthe list editing process, there is performed an operation for deletingthe music piece data file, having been determined as “non-reproducible”(NO determination at step S3), from the music piece reproduction listingpertaining to the recording medium 20, an operation for displaying, inthe music piece reproduction listing. a predetermined mark to excludethe non-reproducible music piece data file from the music piecereproduction listing. Such operations can prevent the music piece,having been determined as “non-reproducible”, from being selected nexttime the reproducing program of FIG. 4 is started.

[0038] Whereas the music piece data reproduction processing is shown inFIG. 4 as executed as software processing by the CPU 1, the reproductionprocessing may of course be executed by a dedicated hardware apparatus.

[0039] Further, whereas the embodiment of the present invention has beendescribed in relation to the case where the external recording medium 20has the unique medium ID previously recorded thereon, the basicprinciples of the present invention may also be applied to recordingmedia where no medium ID is previously recorded thereon. In the casewhere a recording medium 20 having no unique medium ID previouslyrecorded thereon is used in the client terminal 10, the client terminal10 may create a medium ID unique to the medium 20 and then record thethus-created medium ID on the medium 20. For example, when music piecedata are to be downloaded from the server 30, the client terminal 10creates a unique medium ID for a recording medium 20 to be used and thenwrite the thus-created medium ID onto the medium 20 to allowidentification of the recording medium 20. Further, arrangements may bemade for inhibiting use of any recording medium 20 having no uniquemedium ID recorded thereon; in this case, downloading of desired musicpiece data may be inhibited by canceling the data writing operation onthe recording medium 20 at a time point when it is detected that nomedium ID has been read out from the medium 20.

[0040] It should also be appreciated that the external recording media20 to be used in the present invention may be any of writable/readablemedia, such as a flexible or floppy (registered trademark) disk (FD),compact disk (CD-ROM), magneto-optical disk (MO), digital versatile disk(DVD) and magnetic memory.

[0041] Whereas the data recording processing of the present inventionhas been described above in relation to the case where the additional IDand medium ID are set coincide with each other, the present invention isnot so limited; for example, it is only necessary for the additional IDto be an unique ID created on the basis of the medium ID in such amanner that the additional ID is more or less related to the medium ID.Namely, the additional ID may be any suitable ID as long as itsrelationship with the corresponding medium ID can be ascertained and itpermits a determination as to whether the music piece data file havingthe additional ID imparted thereto is a reproducible object. Forexample, the additional ID may be created by encrypting thecorresponding medium ID with a predetermined encryption method. In sucha case, the predetermined encryption method for creating the addition IDmay employ the same algorithm as the above-described second encryptionmethod for encrypting the music piece data, or an algorithm of a thirdencryption method different from the second encryption method. Further,the predetermined encryption method may be arranged to not use, as anencrypting keyword, the medium ID to be encrypted; alternatively, thepredetermined encryption method may be arranged to use, as an encryptingkeyword, the medium ID to be encrypted. In the case where thepredetermined encryption method for creating the addition ID employs thesame algorithm as the above-described second encryption method forencrypting the music piece data, there is advantageously achieved thebenefit that the second encryption section 42 (FIG. 3) for encryptingthe music piece data and the decryption means for decrypting the musicpiece data comprising the second encrypted data (second decryptionmethod used at step S4 of FIG. 4) can be shared not only between theencryption and decryption of the music piece data but also betweenencryption and decryption of the medium ID used for creation of theadditional ID.

[0042] Thus creating the additional ID by encrypting the medium ID will“double-encrypt” content to be recorded on the recording medium 20,thereby ensuring even further enhanced data security. Needless to say,in the case where the additional ID is created by encrypting thecorresponding medium ID, the matching criterion or condition used atstep S3 of FIG. 4 is established in view of the encryption method usedfor the additional ID. For example, an ID obtained by decrypting theencrypted additional ID and the medium ID may be compared for a match,or any other suitable matching condition may be established asappropriate.

[0043] Furthermore, whereas the embodiment of the present invention hasbeen described above in relation to the case where a plurality of musicpiece data files to be recorded on the same recording medium 20 areimparted with a common or same additional ID, the present invention isnot so limited; for example, a plurality of music piece data files to berecorded on the recording medium 20 may be imparted with differentadditional IDs. What is important here is that the music piece datafiles to be recorded on the recording medium 20 have respectiveadditional IDs, unique to the recording medium 20, that are created onthe basis of the medium ID of the recording medium 20 so as tocorrespond to the medium ID. For example, different additional IDs maybe created for the individual data files by encrypting the medium ID inaccordance with different predetermined algorithms corresponding to thedata file numbers; namely, in this case, the additional ID of each ofthe data files is created by encrypting the medium ID using apredetermined algorithm different from those of the other data files tobe recorded on the same recording medium 20.

[0044] In summary, the present invention is characterized in that, onthe basis of a medium ID recorded on a recording medium asidentification information unique to the recording medium, an additionalID related to the medium ID is generated and then the data are encryptedand recorded on the recording medium along with the additional ID. Inreproduction, the medium ID and the additional ID attached to the dataare read out from the recording medium, and then compared to each otherto determine whether both of the medium ID and additional ID meet apredetermined matching criterion or condition. With such arrangements,the present invention can readily sort out data that can be set as areproducible data and non-reproducible data, with the result that theinvention can effectively prevent unfair or unauthorized copying or useof the data through simple and efficient processing.

[0045] The present invention relates to the subject matter of JapanesePatent Application No. 2002-201765 filed on Jul. 10, 2002, thedisclosure of which is expressly incorporated herein by reference in itsentirety.

What is claimed is:
 1. An information recording apparatus comprising: anencryption section that encrypts data to be recorded on a recordingmedium; a generation section that, on the basis of a medium ID recordedas identification information unique to the recording medium, generatesan additional ID related to the medium ID; and a recording section thatrecords the data, encrypted by said encryption section, on the recordingmedium along with the additional ID.
 2. An information recordingapparatus as claimed in claim 1 wherein said generation section uses themedium ID also as the additional ID.
 3. An information recordingapparatus as claimed in claim 1 wherein said generation sectiongenerates the additional ID by encrypting the medium ID.
 4. Aninformation recording apparatus as claimed in claim 1 wherein saidrecording section records the encrypted data and the additional ID onthe recording medium as a single data file.
 5. An information recordingapparatus as claimed in claim 4 which further comprises a displaysection that visually displays, as a single data file, the encrypteddata and the additional ID recorded on the recording medium.
 6. Aninformation reproduction apparatus for reproducing data recorded on arecording medium, said information reproduction apparatus comprising: afirst readout section that reads out, from the recording medium, amedium ID recorded as identification information unique to the recordingmedium, an additional ID related to the medium ID being also recorded onthe recording medium in attached relation to the data; a second readoutsection that reads out, from the recording medium, the additional IDattached to the data; a determination section that compares the mediumID and the additional ID read out by said first and second readoutsections and determines whether both the medium ID and the additional IDmeet a predetermined matching condition, wherein, when the additional IDattached to the data has been determined by said determination sectionas meeting the predetermined matching condition, the data is judged tobe reproducible data.
 7. An information reproduction apparatus asclaimed in claim 6 wherein, on the recording medium, the medium ID isrecorded also as the additional ID.
 8. An information reproductionapparatus as claimed in claim 6 wherein, on the recording medium,information obtained by encrypting the medium ID, is recorded as theadditional ID.
 9. An information reproduction apparatus as claimed inclaim 6 wherein, on the recording medium, the data is recorded alongwith the additional ID as a single data file.
 10. An informationreproduction apparatus as claimed in claim 9 which further comprises adisplay section that visually displays, as a single data file, the dataand the additional ID recorded on the recording medium.
 11. A programcontaining a group of instructions for causing a computer to perform aninformation recording method, said information recording methodcomprising: a step of encrypting data to be recorded on a recordingmedium; a step of, on the basis of a medium ID recorded asidentification information unique to the recording medium, generating anadditional ID related to the medium ID; and a step of recording thedata, encrypted by said step of encrypting, on the recording mediumalong with the additional ID.
 12. A program containing a group ofinstructions for causing a computer to perform an informationreproduction method, said information reproduction method comprising: astep of reading out, from the recording medium, a medium ID recorded asidentification information unique to the recording medium, an additionalID related to the medium ID being also recorded on the recording mediumin attached relation to the data; a step of reading out, from therecording medium, the additional ID attached to the data; a step ofcomparing the medium ID and the additional ID read out by said steps ofreading out and determining whether both the medium ID and theadditional ID meet a predetermined matching condition, wherein, when theadditional ID attached to the data has been determined by said step ofcomparing as meeting the predetermined matching condition, the data isjudged to be reproducible data.